﻿<p>This entity defines a reaction which occurs distributed over a curve.
A curve reaction may be connected with a curve member or curve connection,
or surface member or surface connection.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC4.
</blockquote>

<p><b><u>Coordinate Systems</u></b>:</p>

<p>See definitions at <em>IfcStructuralActivity</em>.</p>

<p><b><u>Topology Use Definitions</u></b>:</p>

<p>Standard Case:<br>
If connected with a curve item, instances of <em>IfcStructuralCurveRection</em> shall not
have an <em>ObjectPlacement</em> nor a <em>Representation</em>.  It is implied that the
placement and representation of the <em>IfcStructuralActivity</em> is the same as the ones
of the member or connection.</p>

<p>Special Case:<br>
If connected with a surface item, instances of <em>IfcStructuralCurveReaction</em> shall
have an <em>ObjectPlacement</em> and <em>Representation</em>, containing an <em>IfcEdgeCurve</em>.
See <em>IfcStructuralActivity</em> for further definitions.</p>

<p class="spec-head">Informal Propositions:</p>

<ol>
  <li>If the curve reaction is of the predefined type CONST,
      <em>SELF\IfcStructuralActivity.AppliedLoad</em> must not be of type
      <em>IfcStructuralLoadConfiguration</em>.</li>
  <li>If the curve reaction is of the predefined type LINEAR,
      <em>SELF\IfcStructuralActivity.AppliedLoad</em> shall be of type
      <em>IfcStructuralLoadConfiguration</em> and shall contain two items.</li>
  <li>If the curve reaction is of the predefined type POLYGONAL,
      <em>SELF\IfcStructuralActivity.AppliedLoad</em> shall be of type
      <em>IfcStructuralLoadConfiguration</em> and shall contain three or more items.</li>
  <li>If the curve action is of the predefined type DISCRETE,
      <em>SELF\IfcStructuralActivity.AppliedLoad</em> shall be of type
      <em>IfcStructuralLoadConfiguration</em> and shall contain two or more items.</li>
  <li>In case of types LINEAR, POLYGONAL, and DISCRETE, the load items shall have
      one-dimensional <em>IfcStructuralLoadConfiguration.Locations</em>, defining the
      location of the result samples in local coordinates of the curve reaction.
      The load items shall be provided in ascending order according to their locations.
      The first and the last load item define the extent of the result distribution.</em>
  <li>If the curve reaction is of the predefined type EQUIDISTANT,
      <em>SELF\IfcStructuralActivity.AppliedLoad</em> shall be of type
      <em>IfcStructuralLoadConfiguration</em> and shall contain two or more items.
      <em>IfcStructuralLoadConfiguration.Locations</em> shall be omitted as it is implicit.
      The load items shall be provided in ascending order.  The first and the last load
      item are located at the beginning and end of the result distribution, respectively.</li>
  <li>All items in <em>SELF\IfcStructuralActivity.AppliedLoad\IfcStructuralLoadConfiguration.Values</em>
      shall be of the same entity type.</li>
</ol>